Variations in crustal structure across the transition from West to East Antarctica, Southern Victoria Land

The crustal structure beneath Ross Island and the Transantarctic Mountains (TAM) in Southern Victoria Land, Antarctica, is inferred using non-linear inversion of receiver functions, derived from teleseismic earthquake data. Intermediate-period waveforms from more than 160 teleseismic earthquakes recorded between January 1994 and January 2000 were used in the analysis. The inversion results confirm a crustal thickness of 19-21 km beneath Ross Island, consistent with previous multichannel seismic work. In addition we observe a crustal thickness of 18-20 km beneath the Ross Sea coastline immediately adjacent to the TAM. Further inland, beneath the TAM, the estimated Moho depths range from 30-33 km (∼30 km from the coast) to 36-40 km (∼85 km from the coast), deepening away from the coast beneath the TAM. These results are in broad agreement with previous seismic and gravity interpretations. Beneath the TAM a sharp mid-crustal discontinuity is present at 8-14 km depth beneath the eastern-most stations, but absent on the western side of the TAM, indicating a spatial change in the mid-crustal composition.